Birr Castle Telescope – Once Worlds Largest

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The Great Telescope Birr Castle

So how did the Irish midlands wind up with the world’s largest and most powerful telescope in 1845? William Parsons, that’s the why. He was a Trinity College educated Yorkshire man and pretty handy at maths by all accounts. The replica telescope currently on the grounds of Birr Castle has a lens 6 feet (1.83m) in diameter. William had it built to replace a smaller 3 foot telescope in its place.

William Parsons, a very very clever man

Construction began in 1842 and wound up in 1845. It stood proudly as the world’s largest for 72 years. Yes 72 years. The 8.3 foot (2.5m) diameter Hooker Telescope on Mount Wilson near Pasadena, Los Angeles finally surpassing in 1917.

The mirrors used in the Birr castle telescope, known as the Leviathan of Parsonstown (Parsonstown being the name of the area at that time), where 5 inches (13cm) thick and weighed about 3 tonnes. This mammoth scope was the worlds austromocial focal point throughout the latter part of the 19th Century.

As aforementioned the current telescope is a reconstruction. As the original plans were lost detective work was required to study photos, drawings, observations and actually parts remaining to build the replica between 1994 and 1997.